Abstract: The development history, strengthening mechanisms, and the degradation laws of microstructural properties during service of 2%-12%Cr ferritic heat-resistant steels for boilers were reviewed. A summary was provided on five newly developed 9%-12%Cr ferritic heat-resistant steels at home and abroad, as well as their processing techniques. Combined with engineering applications, a detailed introduction was given to the reduction adjustment in creep strength and allowable stress for 9%-12%Cr ferritic heat-resistant steels in the United States, Japan, and Europe. Discussions were conducted on issues such as the low hardness of P91 steel, type IV cracking in welded joints, and oxidation corrosion. It is suggested that in-depth research should be carried out on the effects of C, N, B, and rare earth elements on the microstructural properties of heat-resistant steels. Additionally, an analysis should be conducted on the performance degradation and damage mechanism of ferritic heat-resistant steels after deep peak shaving of the unit and long-term service, providing support for unit operation, equipment safety evaluation, and the development of new materials.